The present invention generally relates to electronic devices and more particularly to a mounting device or bracket used for mounting an electronic device on a substrate such as a printed circuit board by surface mounting technology (SMT).
Printed circuit boards are used for supporting electronic devices and for providing interconnections between the devices. The printed circuit board carries thereon a conductor pattern corresponding to the desired wiring or interconnection.
In mounting the integrated circuits or other electronic devices on the printed circuit board, a surface mounting technology is used. In the surface mounting technology, devices having pins provided with a flattened bottom surface as shown in FIG. 1 are used. See devices 2a-2c of FIG. 1. More specifically, a solder pattern is provided on a printed circuit board 1 in correspondence to the pins of the devices to be mounted, and the devices 2a-2c are placed on the surface of the printed circuit board 1 such that each pin of the device contacts with the corresponding solder pattern on the printed circuit board 1. After the devices are thus placed, the printed circuit board 1 is passed through a heating fixture together with the electronic devices placed thereon. Thereby, the solder located under the pin causes a melting called fellow, and the pins are fixed firmly on the solder pattern upon exiting from the heating fixture. This surface mounting technology is easy to implement and reduces the cost of the electronic apparatus.
Meanwhile, there are electronic devices of another type that have interconnection pins that lack the flattened lower surface for surface mounting technology. These pins are adapted to be inserted into through-holes provided on the printed circuit board 1. For example, a connector 3 has a number of pins 3a that are adapted to be accepted by corresponding through-holes 1a on the printed circuit board 1. Further, there are integrated circuits having the PGA structure as shown by an integrated circuit 4. The integrated circuit 4 has a number of interconnection pins 4a arranged in rows and columns at the bottom surface of the body of the integrated circuit, and the integrated circuit 4 is mounted on the printed circuit board 1 such that each pin 4a is accepted by a corresponding through-hole 1b on the printed circuit board 1.
Each through-hole on the printed circuit board 1 carries a metal land, and the pins 3a or 4a that are inserted into the through-holes 1a or 1b are fixed thereto by a solder. The soldering is achieved by dipping the printed circuit board 1 in a molten solder bath (not shown) and pulling up the same subsequently. As the interconnection pins are held firmly in the through-holes, the device of this type is held firmly on the printed circuit board 1 even when a large external force is applied thereto. Thus, this type of device is suitable for the connectors as shown in FIG. 1. Further, the integrated circuits having a very large integration density generally have the PGA structure and cannot use surface mounting technology.
As described above, the soldering of the second type device such as the connector 3 or integrated circuit 4 is achieved by dipping the printed circuit board 1 into the molten solder bath. Alternatively, one has to solder each pin by hand. Thereby, the soldering process of the surface mounting type device cannot be used, as the surface mounting technology uses the heating fixture, not the molten solder bath, for causing the solder to melt. It should be noted that the temperature used to cause the melting of the solder ring is different in the heating fixture and the solder bath. This means that one cannot apply the soldering process for the first type devices 2a-2c of the surface mounting type and the second type devices 3 and that require dipping into the solder bath. In other words, the soldering for the devices 2a-2c has to be done separately from the soldering for the devices 3 and 4. Thus, the conventional electronic devices have suffered from the problem of increased cost associated with the use of two different mounting techniques.